Evolution of Thursday’s thunderstorms

29 06 2012

A series of intense thunderstorms brought exceptionally severe weather across parts of the UK yesterday, causing flash flooding and disruption in many places.

As the storms tracked across the country our observation sites picked up some very heavy hourly rainfall totals, with Scampton in Lincolnshire seeing 28.4 mm falling in an hour.

Several other sites saw hourly totals in excess of 20 mm. This led to flash flooding of properties, roads, and landslides in places.

More than 111,000 lightning strokes were also detected across Europe, with more than 1,000 detected over the UK in a 5 minute period at the peak of activity yesterday.

Hail stones ‘the size of golf balls’ also caused damage in Leicestershire, according to media reports.

The storms were borne out of hot, humid air which had tracked up from the Azores far to the south in the Atlantic. This air mass tracked up on southerly winds, moving over Spain before reaching the UK.

As a result, much of the country saw warm and muggy conditions, with the temperature reaching 28.4 C at St James’s Park, Central London.

The heat and moisture in the air were enough to cause thunderstorms, but the really intense storms were formed as an Atlantic weather front moved in from the west.

As it ‘collided’ with the warm and humid air mass, air rapidly rose to create towering cumulonimbus storm clouds which were laden with water, and ripe for developing hail, thunder and lightning.

This led to several distinct lines of thunderstorms developing along the boundary where the two air masses met.

As shown in the radar sequences below, one line originated in the Cardiff area of south Wales in the early morning. This moved in an east-north-east direction across Worcestershire, Shropshire, the West Midlands and Leicestershire to clear Lincolnshire by late afternoon.

A second line of thunderstorms reached the Lancashire coast around late morning and moved in a NE direction to reach the Newcastle area later in the day, clearing the north east coast by late evening.

There were also torrential downpours across parts of Northern Ireland and western Scotland. Southern parts of England and Wales saw relatively little rain and periods of warm sunshine.





Met Office figures confirm disappointing June

29 06 2012

Update: Provisional Met Office figures for the whole of June are now available at: Met Office confirms wettest June in over a century

Provisional figures from the Met Office to the 27th of June show it has been a disappointing month on all fronts – with many areas being exceptionally wet, very dull and cooler than average.

Currently it is the second wettest June on record for the UK with 130.1 mm of rainfall – just 6 mm off the 2007 total, which was the wettest June in the records which go back to 1910.

It is already the wettest June on record for Wales, with 186.3 mm of rain beating the previous record of 183.1 mm set in 1998. England and Northern Ireland are currently second wettest in the records.

Looking at the figures for the whole of Scotland, it has been a relatively unremarkable month, but there have been big contrasts. North Western areas have seen an exceptionally dry month, while southern and eastern parts have joined the rest of the UK in the wet conditions.

It should be noted that totals for this month so far do not include the heavy rainfall yesterday, and with more rain in the forecast it is likely more records will fall by the end of the month.

It may not be surprising that, with so much rain, sunshine hours have been well down across the UK. There have been 104.2 hours of sunshine so far, just 62% of the long term average (from 1971-2000).

With some sunshine in the forecast, the totals will increase, but it is likely to be one of the duller Junes on record – but it’s not possible to say where it will finish. The current dullest June on record was in 1987, with 115.8 hours of sunshine.

Temperatures have also been below average, with a mean temperature of 11.9 C (0.7 C below average) making for the coolest June since 1991 in the UK.

One of the main reasons for the wet and dull weather so far this month has been the position of the jet stream, which has been much further south than usual. This has meant that rain-bearing Atlantic low pressure systems have been over or close to the UK for the whole month.

max temp min temp mean temp sunshine duration rainfall
Actual Diff from 71-00 avg Actual Diff from 71-00 avg Actual Diff from 71-  00 avg Actual % of 71-00 avg Actual % of 71-00 avg
Regions
UK 15.5 -1.3 8.6 0.2 11.9 -0.7 104.2 62 130.1 179
Eng 16.7 -1.4 9.5 0.4 13 -0.6 99.8 56 131.8 209
Wales 15.8 1 9.4 0.8 12.5 -0.2 106.1 62 186.3 216
Scot 13.6 -1.3 6.8 0.4 10 -0.9 113.1 73 108.1 127
N Ire 15.2 -1.3 8.3 0 11.6 -0.7 91.2 60 151.3 210
Eng & Wales 16.5 -1.4 9.5 0.4 12.9 -0.6 100.7 57 139.3 211
Eng N 15.6 -1.4 8.7 0.2 12 -0.7 85 51 143.5 207
 Eng S 17.2 -1.4 10 0.5 13.5 -0.6 107.6 58 125.6 211




Wet weather has increased pollen count

28 06 2012

In May the Met Office warned that the wet weather we had seen in April was promoting strong grass growth and that this could lead to high grass pollen counts later in the year.

Over recent days, observed pollen counts from the Met Office managed pollen monitoring network, have been very high on dry days at a number of stations, especially across parts of central and southern England. As we move into the weekend pollen counts are expected to remain at moderate to high levels in many areas, depending on the local weather, with further very high counts where the weather is dry.

The graph below shows the difference between this years and last years pollen count:

Patrick Sachon, Health Manager at the Met Office said: “In May we warned that the wet weather could lead to a high grass pollen count during the summer. As expected we have seen some very high pollen counts when the weather has been good. Further high counts are expected during drier and sunnier interludes. We would therefore recommend that hay fever sufferers do all they can to equip themselves to manage their symptoms.”





Dust storm brings Saharan sand to the UK

28 06 2012

Many people across parts of the UK have noticed a layer of light dust on their cars or other surfaces over the past couple of days, but how did it get here?

A big dust storm in the Sahara, around 2,000 miles away, is to blame.

Late last week the storm swept up a large amount of sand and dust from the western Sahara up into the atmosphere.

It then spread westwards out over the Atlantic before getting caught up in southerly winds, dragging it north over Spain before it arrived over the UK mixed up in the warm and humid air which has brought thunder storms and heavy rain to the country.

The dust can get caught up in the rain droplets in clouds, which then fall to the ground. When the water evaporates, a thin layer of dust is left on surfaces, like cars.

Many people noticed this in the South West of the UK yesterday, with the dust then spreading north and east overnight to bring it to a much wider area.

Paul Hutcheon, Deputy Chief Forecaster at the Met Office, said: “We usually see this happen several times a year, particularly in summer when you get these big dust storms in the western Sahara and the southerly winds to bring that dust here.

“This event was a very well-marked example, as you can clearly see the dust as it moves from the Sahara to the UK in the satellite imagery.”

The satellite animation above shows the dust as a bright pink blob over Africa at the start of the sequence, which then moves north over to the UK – initially arriving over the South West, but then moving north and east. You can clearly see the dust-laden airmass of warm and humid air, with a marked boundary to the clear air from a cold front to the west.





Met Office in the News: “Tropical Storms to hit Wimbledon”?

26 06 2012

There have been several articles in the Daily Express over the last couple of days reporting ‘Summer is on the way at last’ with temperatures set to reach 34 Celsius this week and ‘Tropical storms set for Wimbledon’.

These headlines are unfortunately wide of the mark and rather misleading, both by implying that hot and sunny weather is on the way and that Wimbledon will be hit by tropical storms.

Although the Met Office has spoken to the Daily Express, the forecasts featured in the stories have not come from the Met Office, but from an independent forecaster.

The Met Office forecast for this week is for a couple of days of warm, humid and rather cloudy weather across much of the UK, with temperatures reaching 26 or 27 Celsius in any sunshine. For more detail you can find the latest weather forecast on our website.

It is our understanding that the temperatures of 34 deg C referenced in the articles are actually feels like temperatures taken from the website of an independent forecaster rather than actual air temperature. This is not made clear within the article and is potentially misleading.

The inference – through the lack of reference to the original source of the forecasts – that these forecasts have come from the Met Office is very misleading for the public, and potentially damages the reputation not only of the Met Office, but the wider weather forecasting community.

The Met Office is a world leader in meteorological science and our forecasts are recognised the world over as some of the best in the world. We are proud to be trusted to give the best possible guidance on the weather by the public and we report the weather exactly as it is.





Is this the wettest June on record?

26 06 2012

Update: Provisional Met Office figures for the whole of June are now available at: Met Office confirms wettest June in over a century

We all know that, so far, it has been a very wet June in many parts of the UK – but just how wet has it been?

Met Office figures show that, up to the 24th of the month, the UK had seen 122.3 mm of rain –ranking as the third wettest June since records began in 1910 and well over one-and-a-half times the UK average.

So this month is currently just behind the second wettest June in 1912, which saw 124.5 mm of rain, and a little way off the wettest June in 2007, which saw 136.2 mm.

Clearly there are several more days to go and there is some rainfall in the forecast, so not possible to categorically say exactly where the month will finish in the overall records – however it is safe to say it has been a disappointingly wet month.

It’s important to note the rainfall this month hasn’t been evenly spread over the UK. Some areas have seen a great deal of rain, with 52 observation sites breaking record rainfall totals.

Not all of these records are significant as some of stations only have a very short history – for example, Usk in Monmouthshire has only been taking measurements for one year. However, at the other extreme, Otterbourne in Hampshire has been operating for 119 years.

While some areas have already seen record rainfall, others are lingering close to their all-time June minimum. Six stations are currently still below their lowest June rainfall total – but this could change by the end of the month.

What is interesting as that most of the drier stations are in the far north and west of the UK – areas which we would normally expect to see the most rainfall.

UK rainfall map

Map showing rainfall up to the 24 June 2012 compared to the1971-2000 average. Many parts of the country have seen double their normal amount, while the far north west has seen much less than usual.

 

This illustrates the story behind this month’s weather, as the rain-bearing low pressure systems moving in from the Atlantic which normally track to the north of the UK have been taking a much more southerly route, soaking parts of the south while the far north west has remained unusually dry.

One of the main reasons for this is the position of the jet stream. This is a narrow band of fast flowing westerly winds (ie blowing from west to east) high in the atmosphere.

This band moves around and changes its track, and where it sits can impact the UK’s weather. When it flows to the north of the country it can guide low pressure systems away from the UK (but they often clip the far north west of the country as they pass by).

Throughout this June the jet stream has had a much more southerly track, allowing those low pressure systems – with their wind and rain – to come straight over the UK to bring heavy rain to more southern areas while the north west remains relatively unscathed.

You can find out more about the jet stream in our YouTube video.





Heavy rainfall across parts of the UK

23 06 2012

The past two days have seen some exceptional rainfall across the UK, with the heaviest and most persistent rain falling in the North West of England, parts of Northern Ireland and parts of southern Scotland.

Across this area there have been fairly widespread rainfall totals of about 25-50mm of rain in the past 24 hours – from 10am yesterday (22 June) to 10am this morning.

However, some spots saw even more rain in the same period. Here are the wettest places in the past 24 hours:

Blencathra, Cumbria – 93.8mm

Keswick, Cumbria – 88.6mm

Stonyhurst, Lancashire – 74.4mm

Levens Hall, Cumbria – 58.2mm

Morecambe, Lancashire – 57mm

Walney Island, Cumbria – 55.8mm

Preston, Lancashire – 54.8mm

Myerscough, Lancashire – 52.2mm

Bingley, West Yorkshire – 50.2mm

This is in line with the yellow and amber Severe Weather Warnings issued by the Met Office for yesterday’s rain, which forecast 25-50mm of rain across a wide area and up to 100mm possible in some spots.

Rainfall has eased this morning, however heavy rain is expected to sweep in across the UK later this evening and into tomorrow morning and the Met Office has issued further weather warnings.

You can stay up to date with the latest situation by looking at the warnings pages on our website and by staying up to date with our forecasts.

Later on Sunday the weather is expected to improve, giving way to a drier and brighter start to the week with sunny spells and improving temperatures.





Wimbledon weather 2012

22 06 2012

The Wimbledon Championship gets underway next week, and all eyes will be turning to the sky above SW19 as Wimbledon weather watching take hold. The current outlook suggests that after the wet weather over the weekend it will turn a little drier at least for the start of the Championships with a mixture of broken cloud, bright or sunny spells and only a small risk of showers disrupting play. Like this week in the London area, temperatures will also be in the low 20′s  Celsius as well.

The latest forecast from the Met Office is that it will be feeling warmer on Monday with some spells of sunshine and only light winds. It should remain dry throughout, with only a very  small chance of a light afternoon shower disrupting play. Maximum Temperature 22 °C.

To keep up with the latest weather at the championships, visit our dedicated Wimbledon page.

Forecasting at Wimbledon

Like last year, Met Office forecasters will be stationed on site for the duration of the tournament. Our forecasters will combine the latest scientific knowledge and technology from the Met Office’s headquarters in Exeter with on the ground weather reading and assessment. This means that if it’s drizzling on the ground, the on site forecaster can then access information from the Met Office’s arsenal of radars, forecasts and mapping systems to find out which direction it’s moving in the wider area and know whether it will affect play, and for how long.

Even though the new retractable roof means that play on centre court can continue when it’s raining, the weather will still impact on play on the other courts and Met Office forecasts are still used to determine when to close the roof and, perhaps even more importantly, when it is safe to open it again.

Tim Hewson, one of the on-site Met Office forecasters for last year’s tournament, said: “We can’t stop the rain from falling, but we can help the referee organise the tournament around the weather, so that spectators get to watch as much tennis as possible, and so that players don’t risk injury by playing on slippery courts.”

In the video below, Chris Tubbs, who will be on site forecasting this year, talks through the process of forecasting the weather for the championships.

Wimbledon weather facts

  • The warmest Wimbledon Championship on record was 1976, where temperatures averaged at 25.4 C.
  • In 1997, 118.3 mm of rain fell during the championships, making it the wettest Wimbledon on record.
  • Perhaps rather unfairly, Wimbledon has always been associated with bad weather and particularly with rain. But actually play has only been totally rained off 32 times in 125 years.
  • Most years, some rain does fall during the championships, however there have been seven years where rain did not interrupt play at all – 1931, 1976, 1977, 1993 and 1995, 2009 and 2010.

In this video, Johnny Perkins, from the All England Club, explains how the weather affects their planning for the championships and the ideal weather they hope for.





Get your weekend weather on our apps and events calendar this summer

20 06 2012

This weekend is the first weekend of summer (based on the astronomical calendar, meteorologically speaking, summer started on the 1 June) and a number of events are taking place including:

The forecast for the weekend is currently for cooler, windier and much more unsettled weather, with showers and persistent rain at times. There will be some limited sunnier spells, although mainly in the south and east. Where ever you are headed this weekend, you can keep up to date with your local weather on our mobile app for Android or iPhone, or our mobile website. There’s over 5000 forecast locations available including beaches, tourist attractions and national parks.

Visit our events calendar for up-to-date weather for major events taking part this summer, from Wimbledon to the Olympics.





Brighter weather will lead to higher pollen counts

18 06 2012

The recent unsettled weather has kept pollen levels much lower than normal for the time of year. However, this week the weather is expected to be drier, brighter and a little more settled than recent weeks and as a result we expect to see a rise in the amount of pollen. 

Pollen levels, which are mostly from grass pollen at this time of year, could reach high or even very high in central and some southern areas. 

People with hay fever should keep up to date with the pollen forecast this week, which is available on the Met office website and is sponsored by Benadryl®. The pollen forecast uses our latest weather forecast information and combines this with pollen readings from across the UK. 

There are millions of hay fever sufferers across the UK, and the Met Office forecasts provide vital information to help reduce the impact pollen has on their health. 

Health Manager at the Met Office, Patrick Sachon said: ”Following the rain we saw in April and the rain over the last few weeks, grass has grown well, more than last year, when it was much drier. This is therefore expected to cause higher levels of grass pollen than last year. ”The Met Office forecast for the next couple of days is for the UK to be drier and a little more settled that of late in most areas. Occasional showers are likely but with plenty of bright or sunny spells and temperatures in the high teens or low twenties in some parts. This will lead to much higher pollen counts than in recent weeks. This means that those who suffer from hay fever will need to keep an eye the pollen count over the next few days.”

The pollen forecast is part of the wide range of weather-related services offered by the Met Office, which also include the UV index and Heat Health watch.

Find out more about the Met Office pollen forecast.








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